Separation of gases.



subject of the King of Great Britain, residing absorbed gases will be 56per cent. of oxygen 25th April 1905, relates to an im roved JAMES DEWAR,OF CAMBRIDGE, ENGLAND.

SEPARATION Specification of Letters Patent.

OF GASES.

Patented Feb. 11, 1908.

Original application filed April 25, 1905, Serial No. 257,352. Dividedand this application filed January 4- 1906. Serial No. 294.669-

To all whom it may concern:

Be it known that I, JAMES DEWAR, a

at 1 Scroope Terrace, Cambridge, England, professor of chemistry, haveinvented certain new and useful Improvements in Separation of Gases, ofwhich the following is a specification.

This invention, which constituted'a part of my application Serial No.257,352, dated method of separating gases, by aid 0 charcoal.

I have discovered that cooled charcoal exercises a selective action ofabsorption on mixtures of gases or vapors, absorbing some in preferenceto others, insuch manner that practical separation may be obtained inone or several treatments. As an example of this, when dry air in excessof that required for saturation of the charcoal is passed over it at 1800., the mean composition of the and 44 per cent. of nitrogen; furtherfractionation may be obtained of such absorbed gas, by slowly raisingthe temperature of the charcoal, when the air absorbed by the charcoalwill be expelled slowly and may "be collected in separate fractions eachricher in oxygen than the preceding one. In. this manner oxygen ornitrogen may be obtained. By a similar proceeding to the above,fractional separation-of mlxtures of ases and vapors is possible. Thusby coo ing charcoal to 80 C., and passing coal gas over it which hasbeen previously cooled to thesame temperature in order directly toseparate all' the condensable constituents, the charcoal becomes chargedwith the gaseous hydrocarbons and allows the hydrogen and carbonic oxidto escape. On heating the charcoal it evolves these concentrated andgaseous hydrocarbon ya 01's. It is also possible so to cool the c arcoaland the mixed gas passing through it, that a practical separationofgases widely differing in their boiling points may be obtained. As aninstance of this, the most volatile'con. tituents of the air hydrogen,neon and helium, are very imperfectly absorbed in charcoal when cooledto 180 0., so that they are greatly concentrated in that portion of theair which is not condensed by the charcoal;- If such uncondensed gas bepum ed out of the vessel containing the coole charcoal, the hydrogen,helium'and neon will be separated from the bulk of the otherconstituents of the air.

When the object is to separate the less volatile gases of air known aspton and xenon, the mass of charcoal coo ed to the temperature of liquidair is exgosed for a long time to a current of air. 11 allowing thetemperature to rise as reviously explained, the charcoal gives 0 gasricher in oxygen than nitrogen; The gas left in the charcoal about theordinary temperature, can be got out by heating and pumpin and this gas,after separating carbonic acid and volatile organic matter contains thekrypton and xenon, together with nitrogen and oxygen from which mixturethe two first named ases may be separated by liquefaction andfractionation in the usual manner.

Instead of allowing the gases'or vapors absorbed'in the cooled charcoalto expand to the ordinary atmospheric pressure the operation of heatingmay be conducted in closed vessels when the gases will be obtained underpressure,and can be so stored for use.

Having thus described the nature of my said invention, and the bestmeans of carry-- ing the same into practical efiect, I claim 1. Themethod of separating gases or vapors which boil at temperatures below 0C. by absorbing some of the constituents of the mixture, which methodconsists in exposing the mixture to charcoal cooled to a temperaturebelow 0 C. approximately equal to the boiling point of the gas to beabsorbed, and removlng the gases that remain unabsorbed. I,

2. The. method of separatmg gases or vapors which boil at temperaturesbelow.

0 C. by absorbing some of the constituents -of the mixture, which methodconsists in exposing the mixture to charcoal cooled to a temperaturebelow 0 C. approximately equal to the boiling point of that gas amongthe ases to be absorbed which has the lowest-boiling point, then slowlyraising the temperature of the charcoal and collectlng separately; thegases expelled therefrom as the temperature rises.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

JAMES DEWAR.

Witnesses:

Josnrn MILLARD, T. J. Osman. j

